In the past several years, there has been some discussion regarding Smart Homes, in which computers are connected to appliances to control the operation of appliances. For example, these computers are typically said to turn on/off these appliances and to control their operational settings. These systems do not incorporate appliances into the computer system by allowing the appliance to serve as an input/output ("I/O") interface of the computer. Also, these systems are typically said to couple the computers and the appliances through wired communication links. Such wired communication links are disadvantageous as they are difficult and costly to install.
FIGS. 1 and 2 present recent prior art systems that couple a computer to a television ("TV") or a video cassette recorder ("VCR") through a scan or television converter. These converters couple to the TV or VCR through a wired or wireless link. However, these systems differ in that system 100 only utilizes processor 115 to generate RGB data for display, while system 200 utilizes a dedicated graphics accelerator 215 to generate the display data.
As shown in these figures, these prior systems typically include a display device 140 and a computer 105, which includes a bus 110, a processor 115, and a storage 120. Bus 110 connects the various internal modules of the computer. For instance, bus 110 couples processor 115 and storage 120. The storage hardware stores data, such as (1) an application program 125 for performing certain tasks, (2) an operating system 130 for controlling the allocation and usage of the computer's hardware and software resources, and (3) I/O drivers 135 for providing the instruction set necessary to control I/O devices, such as display device 140.
Through bus 110, processor 115 retrieves the data stored in storage 120. The processor then processes the data. At times, the results of this processing is displayed on display device 140, which also couples to bus 110. This display device is typically a PC monitor, such as a cathode ray tube (CRT), for displaying information to a computer user. Other prior art systems utilize a liquid crystal display (LCD) for their display device.
Both display devices 140 of FIGS. 1 and 2 receive the display RGB data from Y-tap connectors or similar pass-through devices (not shown). Also, in both these systems, a digital-to-analog converter (a DAC, which is not shown) converts digital RGB signals to analog RGB signals for display on display devices 140. This DAC can be a part of computer 105, add-in card 210, display device 140, or converters 145.
The Y-tap connector also supplies the RGB data to converters 145, which convert the received signals to analog NTSC or PAL signals supplied to the television or the VCR. Depending on the location of the DACs, these converters can be either scan converters or TV converters. Specifically, if computer 105 or graphics engine 215 contain a DAC, and therefore supply analog RGB data to converter 145, then the converters are scan converters for converting analog RGB data to NTSC or PAL encoded signals. On the other hand, when display device 140 and converter 145 contain the DACs, the converters are TV converters for converting digital RGB data to digital YCrCb data, which are then encoded to NTSC or PAL encoded signals.
Some prior art systems utilize analog wireless links to connect a converter (such as converters 145) to a TV. These analog wireless links are typically radio frequency ("RF") links operating at the 900 MHz frequency range. Also, one prior art system establishes a bi-directional link between the converter and the television. The downstream link used by this prior art system (i.e., the link for forwarding communications from the computer to the television) is also an analog RF link.
There are a number of disadvantages associated with the use of analog RF links. For instance, a receiver receives a degraded signal through such a link because the received signal is composed of a number of signals that correspond to the same transmitted signal but reach the receiver through a variety of paths. In other words, such a link does not offer protection against signal degradation due to the multi-path phenomena.
In addition, such communication links are susceptible to intra-cell interference from noise generated in the communication cell formed around the periphery of the computer and the television. Intra-cell interfering noise can be generated by other appliances or by normal household activity. The intra-cell interfering noise, in turn, can deteriorate the quality of the transmitted data, and thereby deteriorate the quality of the TV presentation.
Analog communication links also are susceptible to inter-cell interference. Such interference can be noise interference from noise sources outside of the communication cell formed by the computer and the television. For instance, such interfering noise can be attributable to RF communications from communication cells (perhaps formed by other computers and televisions) adjacent to the cell formed by the computer and the television. These inter-cell interfering noises can further deteriorate the quality of the transmitted data and the presentation.
Inter-cell interference also refers to eavesdropping on the communications from the computer to the television. The analog communication link between the computer and the television is typically not a secure communication link, because securing such a link is often difficult. Therefore, an eavesdropper outside of the communication cell can tap into the signals transmitted from the computer to the television.
FIG. 3 presents the general operational flow 300 of the prie-r art systems 100 and 200. As shown in this figure, a graphics command is first generated by an application program 305. This command is then passed to the graphics engine 320 (i.e., processor 115 or graphics engine 215) via the operating system and the display driver. In turn, based on the received graphics command, the graphics engine 320 generates RGB data. This RGB data is then routed to PC monitor 140 for display. The converter 325 also receives the RGB data and converts it into analog NTSC or PAL signal supplied to the television or the VCR.
Thus, as set forth in FIG. 3, these prior art systems (1) intercept the RGB signals prepared for display on monitor 140, and then (2) convert this RGB data to analog NTSC or PAL encoded data for a TV display. Because the signals forwarded to the television or the VCR are tapped at such an advanced operational stage, these systems have a number of disadvantages.
For instance, the quality of their TV presentation suffers, because the TV images are generated based on RGB data composed for the PC monitor. In other words, the quality of the display deteriorates once it has to be remapped for analog NTSC after being composed for PC monitor. This remapping is also disadvantageous because it is inefficient and computationally expensive. Numerous calculations that are performed downstream from the drivers to compose the RGB data for the PC monitor have to be recalculated to obtain the graphical images for the television or the VCR.
Consequently, there is a need in the art for a method and apparatus for incorporating an appliance into a computer system. There is also a need for a wireless computer system which uses superior digital wireless communication links. In addition, a computer system is needed which composes output presentations based on the type of the output devices.